The invention relates generally to sprinkler heads used in sprinkler systems for extinguishing and/or controlling a fire, and in particular, to a sprinkler head for use in vacuum dry sprinkler systems.
Dry fire sprinkler systems are known in the industry, and utilized in applications wherein it is disadvantageous to have water or other fire extinguishing fluid residing within the fluid supply lines of the fire extinguishing system when the sprinkler system is not activated. One specific application in which dry sprinkler systems are used include warehouses and other commercial environments wherein the temperature is low enough to cause freezing of the fluid within the pipes.
A common design for a dry sprinkler system is a vacuum dry sprinkler system. In a vacuum dry sprinkler system, the fluid supply pipes operationally connected to the network of sprinklers are continuously exposed to a vacuum which imparts a negative pressure, normally below atmospheric pressure, upon the sprinkler heads of the network. In response to a fire, the individual sprinkler heads within the network are activated by the rupture of a thermally sensitive trigger member carried by each sprinkler head, which in turn subjects the supply lines to a positive pressure, at or above atmospheric pressure. The positive pressure experienced by the system activates a control assembly which subsequently releases water or other fire extinguishing fluid under pressure through the supply lines. This fluid is subsequently expelled from the sprinkler heads in order to suppress or extinguish a fire. An example of a vacuum dry fire sprinkler system is disclosed in U.S. Pat. No. 5,927,406, issued to Kadoche on Jul. 27, 1999.
One problem faced by the sprinkler industry when employing vacuum dry sprinkler systems is overcoming the vacuum pressure once the trigger member is activated. In the sprinkler heads of the sprinkler network, the central orifice of each sprinkler head is sealingly enclosed by a sealing assembly. The sealing assembly is spaced from a deflector, and is maintained in a sealed position by the trigger member normally positioned between the deflector and the sealing assembly. As the central orifice of the sprinkler body is in fluid communication with the supply lines, the sealing assembly is subjected to a vacuum under normal, non-activated conditions. Consequently, when the trigger member is activated by exposure to a preselected temperature, the sealing assembly is released from sealing force imparted by the trigger member. However, given the negative pressure within the central orifice, it has been observed that in many occasions, the vacuum pressure will prevent the removal of the sealing assembly from the orifice outlet. When the sealing assembly remains in the orifice outlet, the vacuum pressure is maintained within the supply lines, and thereby prevents actuation of the vacuum dry sprinkler system in response to a fire.
Another problem experienced by the industry when employing vacuum dry sprinkler systems occurs subsequent to the expulsion of the sealing assembly from the orifice outlet. Once expelled from the outlet, the sealing assembly often contacts and subsequently bounces off the deflector or supporting arms of the sprinkler head and is deflected back towards the orifice outlet. As there still exists a vacuum or negative pressure within the central orifice immediately subsequent to the expulsion of the sealing assembly, when the sealing assembly is deflected back towards the orifice, the sealing assembly is drawn back into the orifice outlet, thereby resealing the orifice outlet, and preventing the vacuum pressure from being broken. This resealing prohibits the activation of the vacuum dry sprinkler system.
The resealing problem has prompted the industry to advance various assemblies intended to prevent resealing, however, such solutions have proven ineffective, or, given their complexity, have greatly increased the cost of manufacturing and installation, and reduced the reliability of the vacuum dry sprinkler system.
Consequently, there exists a need for a vacuum dry sprinkler system having a sprinkler head capable of effectively expelling the sealing assembly from the sprinkler head outlet in response to a fire, and preventing the resealing of the sealing assembly due to deflection off the frame or deflector of the sprinkler head.
The present invention is directed to a vacuum dry sprinkler system utilizing a sprinkler head configured to overcome the vacuum force imparted on the sealing assembly when the thermally responsive trigger is actuated in response to a fire, and further, thrusts the sealing assembly vigorously away from the sprinkler head to thereby prevent resealing caused by the bouncing off or deflection of the sealing assembly off of the frame or deflector of the sprinkler body, and towards the orifice outlet.
According to one aspect of the invention, a vacuum dry sprinkler system includes a fire extinguishing fluid supply line and a control system operably connected to the fire extinguishing fluid supply line which maintains the supply line at a vacuum or negative pressure during a non-activated condition, and is configured to forward fire extinguishing fluid upon exposure to a pressure equal or greater than atmospheric pressure. The system also includes a vacuum dry sprinkler head in fluid communication with the fire extinguishing fluid supply line and includes a sprinkler body with a central orifice and coupled to the fire extinguishing fluid supply line, a pair of frame arms extending a preselected distance from the outlet, a sealing assembly positioned within the orifice outlet, a deflector carried by the frame arms and spaced from the outlet, and a thermally sensitive trigger positioned between the sealing assembly and the deflector which is configured to releasably urge the sealing member into sealing engagement with the central outlet. The sprinkler head also includes a thrust member carried by the frame arms and configured to thrust the sealing assembly away from the sprinkler head to thereby prevent the same from reseating on the orifice outlet when the thermally sensitive trigger is actuated. The thrust member prevents the sealing assembly from contacting the deflector or frame arms of the sprinkler body and subsequently being deflected back into the orifice outlet, and hence, resealing the sprinkler head due to the vacuum pressure of the sprinkler system. By forcing the sealing member away from the sprinkler body, the resealing problem is largely overcome, and results in a more effective and reliable vacuum dry sprinkler system.
According to another aspect of the invention, the vacuum dry sprinkler system sprinkler head includes a spring expulsion assembly carried by the sprinkler body and having at least one spring force sufficient to sequentially overcome the vacuum pressure imparted upon the sealing assembly when the thermally sensitive trigger is actuated in response to a fire to thereby urge the sealing member from the outlet, and prohibit the sealing assembly from resealing the outlet. This spring expulsion assembly maximizes the responsiveness of the vacuum dry sprinkler system by reducing the probability of failure due to the inability to reliably and immediately separate the sealing assembly from the sprinkler body in response to a fire, and prevent subsequent deflection of the sealing assembly back into the orifice outlet. Consequently, the reliability of the vacuum dry sprinkler system is maximized.
According to still another aspect of the invention, the vacuum dry sprinkler system sprinkler head carries an annular expulsion member operably connected to the sealing assembly. The annular expulsion member overcomes the vacuum pressure exerted upon the sealing assembly and forces the sealing assembly from the outlet and away from the sprinkler body to thereby permit atmospheric pressure to enter the fluid supply line and subsequently activate the vacuum dry sprinkler system. The annular expulsion member thus assures that the sealing assembly does not remain within the central orifice after the thermally sensitive trigger has ruptured.
These and other objects, advantages, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.